Finding out your blood type is actually pretty easy. All you need are 3 test tubes with 3 different reagents containing 3 different antibodies: A, B, and Rh. And a sample of blood, of course. Drop some blood into each test tube and watch for the contents to clump. Clumping means the blood is reacting with the same antibodies it has in itself and that’s how scientists figure out our blood type.
The idea is that our blood type is closely tied to our body’s ability to digest certain foods. So every blood type determines a suggested special diet for a person to follow to live their best, healthiest life. This approach was popularized by Dr. Peter J. D’Adamo, after he published a book on this topic in 1996. But there is no agreement as to whether it actually works, because there are no studies that prove this theory right or wrong.